U.S. patent application number 13/048126 was filed with the patent office on 2011-07-07 for biological fluid filtration system and biological filter used therein.
Invention is credited to Chaouki A. Khamis, Majid Zia.
Application Number | 20110163024 13/048126 |
Document ID | / |
Family ID | 26761014 |
Filed Date | 2011-07-07 |
United States Patent
Application |
20110163024 |
Kind Code |
A1 |
Zia; Majid ; et al. |
July 7, 2011 |
BIOLOGICAL FLUID FILTRATION SYSTEM AND BIOLOGICAL FILTER USED
THEREIN
Abstract
A biological fluid processing or fluid filtration system is
provided having novel open and closed loop processing systems
wherein the gases transferred into and out of the system during
processing pass through a porous medium in upstream and/or
downstream gas inlet or outlet housings or vents in a manner which
precludes the fluid being processed or filtered from ever
contacting the housings or vents. Each housing or vent is separated
from the fluid by a column of gas in its respective transfer line.
The upstream gas inlet housing or vent is in communication with the
unfiltered biological fluid, and the downstream gas inlet housing
or vent is in communication with the filtered biological fluid.
Inventors: |
Zia; Majid; (White Bear
Township, MN) ; Khamis; Chaouki A.; (Minneapolis,
MN) |
Family ID: |
26761014 |
Appl. No.: |
13/048126 |
Filed: |
March 15, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12707035 |
Feb 17, 2010 |
7943044 |
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13048126 |
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10962908 |
Oct 12, 2004 |
7501059 |
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12707035 |
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10164668 |
Jun 7, 2002 |
6802425 |
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10962908 |
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09688999 |
Oct 16, 2000 |
6427847 |
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10164668 |
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09272203 |
Mar 19, 1999 |
6171493 |
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09688999 |
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60083484 |
Apr 29, 1998 |
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60078848 |
Mar 20, 1998 |
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Current U.S.
Class: |
210/257.2 |
Current CPC
Class: |
A61M 1/0209 20130101;
A61M 1/0218 20140204; A61M 1/3633 20130101; A61M 1/0231 20140204;
A61M 1/0222 20140204 |
Class at
Publication: |
210/257.2 |
International
Class: |
B01D 63/00 20060101
B01D063/00 |
Claims
1. A fluid filtration apparatus including: a) a filtration device,
said filtration device having a filter media dividing said
filtration device into an up-stream side and a downstream side; b)
a storage container for holding filtered fluid; c) a closed conduit
connected between the downstream side of said filtration device and
said storage container; and, d) a downstream gas inlet in fluid
communication with the downstream side of said filtration device
and selectively open to atmosphere.
2. The fluid filtration apparatus defined in claim 1, wherein said
downstream gas inlet includes; a) an inlet open to atmosphere; b)
an outlet connected to a vent line; and, c) at least one layer of a
porous medium interposed between said inlet and said outlet.
3. The fluid filtration apparatus defined in claim 2, wherein said
downstream gas inlet further includes a cap for the selective
opening and closing of said inlet.
4. The fluid filtration apparatus defined in claim 2, wherein said
at least one layer of a porous medium is a bacterial retention
medium.
5. The fluid filtration apparatus defined in claim 2, wherein said
at least one layer of a porous medium is a viral retention
medium.
6. A fluid filtration apparatus including: a) a filtration device,
said filtration device having a filter media dividing said
filtration device into an up-stream side and a downstream side; b)
a storage container for holding filtered fluid; c) a conduit
connected between the downstream side of said filtration device and
said storage container; and, d) a vent line in fluid communication
with the downstream side of said filtration device, selectively
open to atmosphere, and elevated above the filtration device.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 12/707,035, filed Feb. 17, 2010, which is a continuation of
U.S. application Ser. No. 10/962,908, filed Oct. 12, 2004, which is
a divisional application of U.S. application Ser. No. 10/164,668,
filed on Jun. 7, 2002, which is now U.S. Pat. No. 6,802,425, which
is a divisional application of U.S. application Ser. No.
09/688,999, filed Oct. 16, 2000, which is now U.S. Pat. No.
6,427,847, which is a divisional application of U.S. application
Ser. No. 09/272,203, filed Mar. 19, 1999, which is now U.S. Pat.
No. 6,171,493. U.S. application Ser. Nos. 10/962,908 and
10/164,668, U.S. Pat. No. 6,427,847, and U.S. Pat. No. 6,171,493
are each hereby incorporated by reference as if set forth in their
entirety herein. U.S. application Ser. No. 10/962,908 is pending as
of the filing date of the present application.
[0002] U.S. application Ser. No. 09/272,203, from which priority is
claimed above, claims the benefit, Under 35 U.S.C. 119(e), of
provisional application No. 60/078,848, and of provisional
application No. 60/083,484. The provisional application 60/078,848
and 60/083,484 are hereby incorporated by reference as if set forth
in their entirety herein.
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention
[0004] The present invention relates to a method and apparatus for
processing biological fluids into their therapeutically valuable
components. More particularly, the present invention relates to a
method and apparatus for processing donated blood into its
therapeutically valuable components. Most particularly, the present
invention relates to an improved method and apparatus for
processing donated blood into its therapeutically valuable
components which uses improved open-loop and closed-loop systems to
substantially increase the recovery of all the blood products from
the donated blood.
[0005] 2. Discussion of the Related Art
[0006] Methods and apparatus for processing blood are well known in
the prior art. U.S. Pat. No. 3,892,236 to Djerassi shows an
apparatus for the continuous withdrawal of blood from a human
donor, forced extracorporeal circulation of blood of the donor with
separation of granulocytes, and return by gravity of the
leukocyte-poor whole blood to the donor.
[0007] U.S. Pat. No. 5,126,054 to Matkovich shows a venting means
for venting gas from the transfer line of a liquid delivery system
comprising a housing, a first, liquid-wettable, microporous
membrane carried in said housing so as to be in communication with
the transfer line, and a second, non-liquid-wettable, gas permeable
microporous membrane superimposed on said microporous membrane to
the outward side of the housing. Gas in the delivery system is
vented from the system so long as the first microporous membrane
remains unwetted by the delivery liquid.
[0008] U.S. Pat. No. 5,451,321 to Matkovich shows biological fluid
processing assemblies having a gas inlet, and/or a gas outlet.
[0009] While these devices are generally satisfactory, some of the
methods and apparatus of the prior art leave a large amount of
biological fluid trapped in various elements of the fluid
processing apparatus. While the aforementioned patent U.S. Pat. No.
5,451,321 to Matkovich provides for liquid trapped in various
elements of the blood processing system to be recovered either by
causing a volume of gas behind the entrapped liquid to push the
liquid through those elements and into the designated collection
bag, or by pulling the entrapped liquid into the designated
collection bag by a pressure differential (e.g. gravity head,
pressure cuff, suction and the like), the system still has several
drawbacks. One drawback is that they require one or more
nonwettable, gas permeable, membranes. This requirement can lead to
increased costs over wettable membranes.
[0010] Therefore, those skilled in the art continue to search for a
method and apparatus to provide for optimal recovery of the
biological fluid from biological fluid processing systems, cost
reduction and ease of use, and have developed novel open and closed
loop systems and methods associated therewith to achieve this
goal.
SUMMARY OF THE INVENTION
[0011] The problems of the prior art are solved by the present
invention utilizing novel open and closed loop biological fluid
processing systems which all share the concept that the gases
transferred into, out of, or within the biological fluid processing
system have the transfer lines arranged or configured in a manner
which precludes the biological fluid from ever contacting the
upstream and downstream gas inlet or outlet housings or vents, or
bypassing the fluid filtration or leukocyte depletion device. Gases
are transferred into and out of the biological fluid processing
systems through a porous medium in the upstream and downstream gas
inlet housings or vents.
[0012] Each housing or vent is separated from, and in communication
with the biological fluid by a column of gas in the transfer lines.
The upstream gas inlet housing or vent is in communication with the
unfiltered biological fluid and the downstream inlet or vent is in
communication with the filtered biological fluid.
[0013] In one embodiment of the present invention, a biological
fluid filtration apparatus is provided which includes a fluid
filtration or leukocyte depletion device having an inlet and an
outlet, a fluid container upstream from and elevated above said
fluid filtration or leukocyte depletion device and having an
outlet, a first conduit in fluid communication with the outlet of
said fluid container and the inlet of said fluid filtration or
leukocyte depletion device, a receiving container downstream of
said fluid filtration or leukocyte depletion device and having an
inlet, a second conduit in fluid communication with the inlet of
said receiving container and the outlet of said fluid filtration or
leukocyte depletion device, an upstream gas inlet having one of its
quadrature ends elevated above said fluid container, and having its
other end in fluid communication with said first conduit, and a
downstream gas inlet having one of its' end elevated above said
fluid container, and having its' other end in fluid communication
with said or leukocyte depletion or fluid filtration device.
[0014] In another embodiment of the present invention, there is
provided a closed loop fluid filtration or leukocyte depletion
device including a fluid filtration or leukocyte depletion device
having an inlet and an outlet, a fluid container upstream from, and
elevated above, said fluid filtration or leukocyte depletion device
and having an outlet, a first conduit in communication with the
outlet of said fluid container and the inlet of said fluid
filtration or leukocyte depletion device, a receiving container
downstream of said fluid filtration or leukocyte depletion device
and having an inlet, a second conduit in fluid communication with
the inlet of said receiving container and the outlet of said fluid
depletion device and a bypass line in fluid communication with said
fluid container and said receiving container and having a loop
portion elevated above said fluid container.
[0015] In yet another embodiment of the present invention the
upstream gas inlet is eliminated and the downstream gas inlet is
connected to the receiving container instead of the fluid
filtration or leukocyte depletion device.
[0016] In another embodiment of the present invention, the
downstream gas inlet may be eliminated.
[0017] In still another modification of the present invention, the
upstream gas inlet housing or vent and the downstream gas inlet
housing or vent may be part of the same inlet device.
[0018] Thus, it is an object of the present invention to provide an
improved method and apparatus for filtering biological fluids.
[0019] It is a further object of the present invention to provide
an open gas vent that prevents premature gas introduction into the
fluid stream in a biological fluid processing system.
[0020] It is a further object of the present invention to provide
an open loop biological fluid processing system with transfer lines
or conduits arranged or configured in a matter which precludes the
biological fluid from contacting the upstream and downstream gas
inlet housings or vents, or bypassing the biological fluid
depletion device.
[0021] Another object of the present invention is to offer a wider
choice of materials which may be used in the gas inlet housings or
gas outlet housings or vents of biological fluid filtration
systems. The present invention does not require wettable membranes.
The choice of membranes for the present invention is not
limited.
[0022] Another object of the present invention is to provide a
system of the foregoing nature where gas is transferred into and
out of the biological fluid processor through porous medium in the
upstream and downstream gas vents.
[0023] A still further object of the present invention is to
provide an open loop system of the foregoing nature where each gas
vent is separated from, and in communication with the biological
fluid by a column of gas in the transfer lines or conduits.
[0024] A still further object of the present invention is to
provide an open loop biological fluid filtration system of the
foregoing nature wherein the upstream gas inlet housing or vent,
and the downstream gas inlet housing or vent may be a portion of
the same inlet device.
[0025] A still further object of the present invention is to
provide a closed loop biological fluid filtration system having a
bypass line bypassing the biological fluid filtration device, the
bypass line is arranged such that a column of gas separates the
unfiltered biological fluid upstream of the filtration device from
the filtered biological fluid downstream of the biological fluid
filtration device.
[0026] A further object of the present invention is to provide an
open loop biological fluid filtration system having an upstream gas
inlet elevated above the level of the biological fluid container
and having a satellite bag connected to the biological receiving
fluid container.
[0027] Further objects and advantages of the present invention will
be apparent from the following description and appended claims,
reference being made to the accompanying drawings forming a part of
the specification, wherein like reference characters designate
corresponding parts in the several views.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1 is an elevational view of a prior art biological
fluid filtration system;
[0029] FIG. 2 is an elevational view of a construction embodying
the present invention;
[0030] FIG. 3 is an elevational view showing a modification of the
construction shown in FIG. 2;
[0031] FIG. 4 is an elevational view of a further modification of
the construction shown in FIG. 2;
[0032] FIG. 5 is an elevational view showing a further modification
of the construction shown in FIG. 2;
[0033] FIG. 6 is an elevational view of a closed loop construction
embodying the present invention;
[0034] FIG. 7 is an elevational view showing a modification of the
construction shown in FIG. 6;
[0035] FIG. 8 is an elevational view of a further modification of
the construction shown in FIG. 6;
[0036] FIG. 9 is an elevational view showing a further modification
of the construction shown in FIG. 6;
[0037] FIG. 10 is an elevational view showing a further
modification of the construction shown in FIG. 6;
[0038] FIG. 11 is an elevational view showing a further
modification of the construction shown in FIG. 6;
[0039] FIG. 12 is an elevational view of a construction embodying
the present invention utilizing a satellite bag;
[0040] FIG. 13 is a perspective view of a biological fluid filter
construction embodying the present invention;
[0041] FIG. 14 is a front elevational view of the construction
shown in FIG. 13;
[0042] FIG. 15 is a sectional view, taken in the direction of the
arrows, along the section line 15-15 of FIG. 14;
[0043] FIG. 16 is a sectional view, taken in the direction of the
arrows, along the section line 16-16 of FIG. 14;
[0044] FIG. 17 is a sectional view, taken in the direction of the
arrows, along the section line 17-17 of FIG. 14;
[0045] FIG. 18 is a front elevational view of the inlet portion of
the construction shown in FIG. 13;
[0046] FIG. 19 is a rear elevational view of the construction shown
in FIG. 18;
[0047] FIG. 20 is a front elevational view of the outlet portion of
the construction shown in FIG. 13;
[0048] FIG. 21 is a rear elevational view of the construction shown
in FIG. 20;
[0049] FIG. 22 is a modification of the construction shown in FIG.
13;
[0050] FIG. 23 is a diagrammatic view of the filter medium shown in
the construction of FIG. 22;
[0051] FIG. 24 is a diagrammatic view of a further modification of
the construction shown in FIG. 13; and
[0052] FIG. 25 is a diagrammatic view of the filter medium shown in
the construction shown in FIG. 24.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0053] The aforementioned U.S. Pat. No. 5,451,321 to Matkovich
shows a biological fluid processing assembly for filter biological
processes such as blood. An example of the Matkovich apparatus is
illustrated in FIG. 1. The apparatus has a blood collection bag 30
connected by a first conduit 31 to a leukocyte depletion device 32.
The leukocyte depletion device 32 is connected by a second conduit
33 to a blood receiving bag 34. A gas inlet 35 having a cover or
cap 36, is provided in fluid communication with the first conduit
31 downstream of said collection bag 30, and a gas outlet 37 is
provided in second conduit 33 downstream of the leukocyte depletion
device 32.
[0054] In one embodiment of the prior art, a first clamp 38 is
placed on first conduit 31 downstream of the blood collection bag
30 and upstream of the gas inlet 35, and a second clamp 39 is
placed on the second conduit 33 downstream of the gas outlet 37. In
a typical operation the blood collection bag 30 is sterile and is
connected to the conduit 31 as illustrated. The gas inlet 35 is
comprised of a housing 41 and a porous medium barrier 42 in
addition to cover or cap 36. Additional details of the barrier 42
may be obtained by reference to U.S. Pat. No. 5,451,321.
[0055] Prior to the start of blood processing, the inlet clamp 38,
the outlet clamp 39, and the gas inlet 35 are all closed. The blood
processing is initiated by opening the inlet clamp 38, and allowing
the blood to drain from the blood collection bag 30. A column of
blood flows through the first conduit 31 into the leukocyte
depletion device 32 displacing any gas within the blood processing
system. No blood enters the gas inlet device 35 since the gas inlet
is closed. The displaced gas is expelled from the system through
the gas outlet 37 since the second clamp 39 is closed. As
substantially all the gas is expelled from the first conduit 31 and
the portion of the second conduit 33 leading to the gas outlet 37,
the porous medium is wetted by the blood, and the blood flow seizes
or stops at the liquiphobic bearer in the gas outlet 37.
[0056] Once the gas outlet 37 is wetted, the second or outlet clamp
39 is opened, and filtered blood flows into the blood receiving bag
34. The gas outlet 37 need not be closed prior to opening of the
outlet clamp since the gas outlet is sealed by the wetted porous
medium. Blood flows from the collapsible blood container or bag 30
through the leukocyte depletion device 32 and into the blood
receiving bag 34 until equilibrium is reached within the system and
blood ceases to flow. At this point, all of the blood has not been
processed through the leukocyte depletion device 32. The first
conduit 31, the filter device 32, and the second conduit 33 are
filled with blood.
[0057] Removing the cover or cap 36 from the gas inlet 35 allows
gas to enter the processing system and drive the blood through the
leukocyte depletion device 32. However, since the filter medium 32A
within the leukocyte depletion device 32 is wetted, the flow of
blood seizes when gas fills the upstream chamber of the filter.
When the blood flow seizes, the second or outlet clamp 39 is
closed. It can be seen that, at this point, the downstream side of
the leukocyte depletion device 32, and the entire second conduit 33
are filled with blood. With ever increasing need for blood and
blood products, those skilled in the prior art have strived to
increase the recovery of blood, and such a relatively large
quantity of blood being left in the device of the prior art is no
longer satisfactory.
[0058] In order to solve the recovery problems present in the prior
art devices, the open-loop construction shown in FIG. 2 has been
developed. There is shown a biological fluid filtration system 44
having a leukocyte depletion device 45 with a filter medium 46, an
inlet 47, and an outlet 48. The leukocyte depletion device may be
such as the biological fluid filter shown in provisional
application Ser. No. 60/083,484, which has been incorporated herein
by reference, or any other suitable fluid filtration or leukocyte
depletion device.
[0059] A blood container 49 is provided upstream from, and elevated
above said leukocyte depletion device 45. Blood container 49 is
connected to, or in fluid communication with, said leukocyte
depletion device 45 through first conduit 50.
[0060] There is also provided a blood receiving container 52
downstream of said leukocyte depletion device 45. Leukocyte
depletion device 45 is connected to blood receiving container 52
through second conduit 54. An upstream gas inlet 56 is provided in
fluid communication with said first conduit 50, and a downstream
gas inlet 58 is provided in fluid communication with said leukocyte
depletion device 45, downstream of said filter medium 46.
[0061] An inlet clamp 60 and an outlet clamp 61 may be provided. It
should be understood that one or more of inlet clamp 60 and/or
outlet clamp 61 may be provided, and be well within the scope of
the present invention.
[0062] Upstream gas inlet 56 may take the form of a vent line 62
being connected to an upstream gas inlet housing 64. Vent line 62
may have a U-shaped portion 62A to prevent drawing of gas into
biological fluid filtration system 44 until substantially all of
the biological fluid has drained from the biological fluid
container 49. The other end of vent line 62 should be at a
sufficient height such that it is always positioned above the level
of the fluid in the biological fluid container 49.
[0063] Upstream gas inlet housing or vent 64 has an inlet 65 and an
outlet 66. Interposed between the inlet 65 and the outlet 66 in a
sealing relationship is at least one layer of a porous medium 67.
The porous medium may be such as a bacterial retention medium, a
viral retention medium, or other suitable medium.
[0064] In a similar manner, the downstream gas inlet 58 may
comprise a second vent line 70 connected to a downstream gas inlet
housing or vent 71 having an inlet 72 and an outlet 73. A cap or
other closure 74 may be used in connection with the opening and the
closing of inlet 72. Interposed in the housing 71, between the
inlet 72 and the outlet 73 is a second porous medium 76. The second
porous medium 76 may also be such as a bacterial retention medium,
a viral retention medium, or other suitable medium.
[0065] As illustrated, upstream gas inlet housing 64 and downstream
gas inlet housing 71 may be provided in a single novel inlet device
80 having a barrier or wall 81 which prevents fluid communication
between the upstream gas inlet porous medium 67 and the downstream
gas inlet porous medium 76. The upstream medium 67 and the
downstream medium 76 may then be formed of a single sheet.
[0066] The upstream gas inlet 56 and the downstream gas inlet 58
may be placed in any practicable location as long as they are
located such that the blood product being filtered never contacts
the porous medium 67. In the preferred embodiment illustrated the
porous medium 67 contained within the housing 64 is elevated above
the blood container 49, but other locations are well within the
scope of the present invention.
[0067] In the method of blood processing embodying the present
invention, the inlet clamp 60 and the outlet clamp 61 are initially
closed. The cap or closure 74 covering the inlet 72 of downstream
gas inlet device, housing, or housing portion 71 is also in
place.
[0068] The blood processing is initiated by opening the inlet clamp
60 and allowing the biological fluid to flow through the first
conduit 50. As the fluid flows past the junction 50A, some of the
fluid will flow into the upstream gas inlet 56 through vent line
62. A column of liquid of a predetermined, desired, length (shown
as dimension A in FIG. 2), between the junction 50A and the bottom
of the loop portion of 62A, prevents gas entry into the system
until substantially all of the biological fluid has been drained
from the biological fluid container 49.
[0069] The upstream gas vent may be thought of as a manometer
measuring the pressure at the junction 50A. As the level of fluid
within the biological fluid container 49 decreases, the pressure at
the junction 50A decreases and, therefore, the height of the fluid
in the vent line 62 decreases. When substantially all of the
biological fluid has drained from the biological fluid container
49, the atmospheric pressure acting on the column of fluid within
the vent line 62 will cause all of the fluid within the upstream
gas inlet 56 to drain into the conduit 50. The remaining fluid
contained with the upstream gas inlet line 62 is drained into the
conduit 50 because the upstream gas inlet is open to atmosphere.
Thus, dimension A in FIG. 2 must be of sufficient distance such
that the above described sequence of events occur. At this point,
the leukocyte depletion device 45 downstream of the filter medium
46 and the second conduit 54 between the leukocyte depletion device
45 and the blood receiving container 52, are all filled with
filtered biological fluid.
[0070] The filtered biological fluid or blood downstream of the
filter medium 46 in the leukocyte depletion device 45 may now be
recovered by opening the cap or closure 74 covering the inlet 72 of
downstream gas inlet device, housing, or housing portion 71. In
place of cap 74, a clamp (not shown) could be used on second vent
70.
[0071] After this step substantially all of the blood previously
unrecovered by the prior art devices is in the blood receiving
container 52. Any gas in the receiving container 52 and/or second
conduit 54 downstream of the disconnecting point of the blood
receiving container 52 may be pushed back up into the second
conduit 54 by gently squeezing the blood receiving container 52,
and then the outlet clamp 61 can be closed.
[0072] As is now evident, the construction shown in FIG. 2 provides
an easy method of drainage of substantially all of the biological
fluid from the receiving bag 52 through the leukocyte depletion
device 45. In addition, the biological fluid filtration system 44
in its preferred embodiment utilizes only a single housing in the
inlet device 80, and a single layer of porous medium and
substantially all of the filtered biological fluid is recovered.
The system has a lower number of parts, is easier to manufacture,
and recovers more biological fluid at a lower per unit biological
fluid processing cost.
[0073] Alternate embodiments of the construction shown in FIG. 2
are illustrated in FIGS. 3-5, with like numerals designating
corresponding parts in the several views. Their operation can
easily be understood by those skilled in the art in view of the
foregoing description.
[0074] A modification of the present invention utilizing only the
upstream gas inlet 56 and a satellite bag 83 is shown in FIG. 12.
Satellite bag 83 is connected in fluid communication with blood
receiving container 52 by satellite conduit 84. Satellite clamp 85
opens and closes satellite conduit 84. In this embodiment of the
present invention, the satellite bag is used to vent the gas
displaced from the receiving container 52. The volume of the
satellite bag 83 should be sufficient to accept all of the gas
displaced. After all the blood has flowed into the receiving
container 52, the container is gently squeezed until all of the gas
is vented past the satellite clamp 85, at which time the satellite
clamp 85 is closed.
[0075] Referring now to FIG. 6, there is shown a closed loop
biological fluid filtration system 90. As in previous embodiments
of the present invention, there is a leukocyte depletion device 45
having a filter medium 46, an inlet 47, and an outlet 48. The
filter medium 46 is interposed in a sealing relationship between
the inlet 47 and the outlet 48. The system 90 also includes a blood
container 49 connected by first conduit 50 to the inlet 47 of
leukocyte depletion device 45. Inlet clamp 60 is provided as
before.
[0076] Provided downstream of the leukocyte depletion device 45 is
a blood receiving container 52. A second conduit 54 is connected
between the outlet 48 of the leukocyte depletion device 45 and the
inlet of the blood receiving container 52. Used in place of the
upstream gas inlet 56 and a downstream gas inlet 58 is a by-pass
line 91, which may be opened and closed by by-pass clamp 92. A
first end of the by-pass line 91 is connected in fluid
communication with the blood container 49 proximate the outlet
thereof, and the other end of the by-pass line 91 is connected in
fluid communication with the blood receiving container 52 proximate
the inlet thereof. The loop portion 93 of the by-pass line 91 is
positioned such that when the blood container 49 is full of blood,
the blood will not reach the loop portion 93 and thus, there can be
no flow of blood through the by-pass line. One such position is
illustrated in FIG. 6 with the loop portion 93 elevated above the
blood container 49.
[0077] In place of loop portion 93, a one way check valve or other
device may be used such that a column of gas will always separate
the unfiltered biological fluid upstream of the filtration device
from the filtered biological fluid downstream of the leukocyte
depletion device 45. The positioning of the loop portion 93, and
the bypass line 91 may also be varied to accomplish this.
[0078] The method of operating the closed loop embodiment of the
invention differs in several respects from the method used with the
open loop embodiment. As illustrated in FIG. 6, the additional
by-pass clamp 92 is needed because no gas inlet or gas outlet
devices are provided, as were necessary in the prior art. Prior to
the start of blood processing, the inlet clamp 60 is closed and the
by-pass clamp 92 is open. The blood processing is initiated by
opening the inlet clamp 60 and allowing blood to drain from the
blood container 49 through first conduit 50 into the leukocyte
depletion device 45 and therethrough to the blood receiving
container 52. The blood does not by-pass the leukocyte depletion
device 45 because of the loop portion 93 of the by-pass line 91
being elevated to a sufficient height. The gas within the closed
loop biological fluid filtration system 90 is displaced by the
blood flow into the blood receiving container 52. As the blood
container 49 approaches its nearly empty condition, the gas stored
within the receiving container 52 automatically flows through the
by-pass line 91 into the blood container 49 and allows
substantially all of the blood to be processed through the
leukocyte filtration device 45. It is important to note that the
chamber of the leukocyte depletion device 45 downstream of the
filter media 46 at this point will be filled with blood, as will
the second conduit 54 between the leukocyte depletion device and
the blood receiving container 52. If there is any gas left in the
receiving container 52 it may be displaced into the by-pass line 91
by closing the outlet clamp 61, gently squeezing the blood
receiving container 52 and closing the by-pass clamp 92. In this
embodiment of the invention comprising the closed loop biological
fluid filtration system, the chamber downstream of the filter
medium 46 in the leukocyte depletion device 45 is not drained of
blood, nor is second conduct 54. However, the inlet device and the
outlet devices of the prior art are eliminated, and a simplified
system is provided.
[0079] Additional modifications of the closed loop biological fluid
filtration system 90 are shown in FIGS. 7-11. Their operation can
be understood by those skilled in the art from the foregoing
description.
[0080] A more detailed description of the biological fluid filter
can be had by referring to FIGS. 13-25. The biological fluid filter
100 consists of an inlet section 101 and an outlet section 102.
Referring to FIGS. 14 and 15, the inlet section 101 of biological
fluid filter 100 has an inlet 103, including port 103A,
communicating with first passage 104, which is in fluid
communication with first or inlet chamber 105 through first port of
outlet 104A. Further, biological fluid filter 100 has a second
passage 106 in fluid communication with both, first or inlet
chamber 105, and first vent chamber 107.
[0081] The outlet section 102 has a second vent chamber 110 in
fluid communication with a third passage 111. Third passage 111 is
in fluid communication with outlet 112 through port 112A. A fourth
passage 113 is in communication with the third passage 111 and the
second or outlet chamber 115. A vent filter element 117 separates
the first vent chamber 107 from the second vent chamber 110, and is
held in place by means to be described in more detail
hereinbelow.
[0082] Similarly, a biological filter element 119 separates the
first or inlet chamber 105 from the second or outlet chamber 115.
Both the vent filter element 117 and the biological filter element
119 may consist of one or more layers, and be made of a wide
variety of filter materials. In the embodiment illustrated, they
are liquiphilic.
[0083] In the preferred embodiment, the vent filter element 117,
and the biological fluid filter element 119, are made of the same
filter medium, which may be such as glass or nylon fibers. In use,
a fluid container (not shown), such as a blood container is placed
in fluid communication with inlet port 103A. Similarly, a
biological fluid receiving bag (not shown) is placed in fluid
communication, by means well known in the art, with outlet port
112A. Fluid flow is initiated and blood flows in the inlet port
103A, through the first passage 104 and through first outlet 104A
into inlet chamber 105.
[0084] In operation, as the blood enters the inlet chamber 105, the
blood may wick into the filter element 119. The blood may wick into
the filter element 119 faster, or slower, than the blood level
rises in the first or inlet chamber 105. The rate at which the
blood wicks into the filter element 119 will depend on the
properties of the filter medium being chosen, and the biological
fluid being filtered. These properties include the pore size of the
medium, the density of the biological fluid, the surface tension of
the biological fluid, and the contact angle of the solid-liquid-gas
interface. While the blood level is rising in the inlet chamber
105, any air entrapped in chamber 105 is either passing through a
portion of the filter element 119 which is not yet wetted, or is
proceeding through second passage 106 and being vented out the vent
filter element 117.
[0085] As the blood level continues to rise in inlet chamber 105,
at some point, the biological filter element 119 will be
sufficiently "wetted", and the biological fluid being filtered will
"breakthrough" the filter element 119, and will start flowing into
outlet chamber 115. The fluid breakthrough depends on the pore size
of the material, the surface tension and the contact angle, as well
as the pressure differential across the filter element 119.
[0086] Due to the pressure differential across the biological
filter element 119, the biological fluid continues to flow up into
second passage 106. If the pressure differential is sufficient, the
biological fluid will contact the vent filter element 117, which is
the preferred embodiment. If the vent filter element 117 is also
made of a liquiphilic media, it will become "wetted out". However,
by this time all the gas entrapped in inlet chamber 105 has either
passed previously through biological filter element 119 or through
vent filter element 117 and accomplished one of the objects of the
invention.
[0087] Referring now to FIGS. 14-19, the construction of the inlet
section 101 of the biological fluid filter 100 may be clearly
understood. The biological fluid filter 100 includes an inlet
section 101 which is bonded to an outlet section 102 by a seal 130.
The seal 130 is preferably an ultrasonic seal. It can be understood
by those skilled in the art that other seals such as heat seals,
adhesive seals, or any other air tight seal may be used.
[0088] Inlet section 101 includes a recessed top wall 131, and down
standing side walls 132 extending around the periphery of the
recessed top wall 131. A down standing peripheral ridge 133 extends
around the periphery of the down standing side wall 132 and forms a
part of the mechanism which holds the vent filter element 117 and
the biological filter element 119 in place, as will be more fully
explained hereinafter. A first protuberance 135 extends from the
recessed top wall 131, and carries the inlet 103 and first passage
104 as previously described. First or outlet port 104A which is in
fluid communication with the first passage 104 can be seen in FIG.
19. A recess 136, provided by the combination of the top surface of
the recessed top wall 131 and the peripheral side walls 137 almost
completely surrounds the protuberance 135.
[0089] A peripheral flange 138 depends from the peripheral sidewall
137 and forms a groove 139 extending around the periphery of the
inlet section 101 of the biological fluid filter 100. The groove
139 forms a portion of the means by which the seal 130 between the
inlet section 101 and the outlet section 102 of the biological
fluid filter 100 is formed. A plurality of down standing ribs 142
are provided on the lower surface of the recessed top wall 131 for
purposes to be described.
[0090] The inlet portion 101 of the biological fluid filtration
device also has an extended portion 145 which contains second
passage 106 (FIG. 15) in fluid communication with first vent
chamber 107. The same flange 138 and groove 139 are provided in the
extended portion 145 of the inlet section 101 as are provided in
the remainder of the inlet section 101, so that the inlet section
101 will properly mate with the outlet section 102 to be described.
A circular ridge 147 is provided about the first vent chamber 107
to aid in holding the vent filter, as will be further
described.
[0091] Referring now to FIGS. 15-17 and 20-21, the construction of
the outlet portion 102 of the biological fluid filter 100 will be
clearly understood. The shape of the outlet section 102 of the
biological fluid filter 100 is complimentary in shape to the inlet
section 101 so that the inlet section 101 may act as a closure to
the outlet section 102, or vice versa. It can easily be understood
by those skilled in the art that the biological fluid filter 100
may be of any desired shape, such as the generally oval shape thus
far described, the diamond shape of the modification shown in FIG.
22 or 24, or any other desired shape. Similar to the inlet section
101, the outlet section 102 of the biological fluid filter 100 has
a bottom wall 150 and upstanding sidewall 151. The top of the
upstanding sidewall 151 fits into the groove 139 in the inlet
portion 101, and is preferably sonically welded to form the seal
130. A second protuberance 154 is provided on the exterior portion
of the bottom wall 150 and carries the third passage 111, fourth
passage 113, and a portion of the vent chamber 110. A second
circular ridge 155, complimentary in shape to the circular ridge
147, is provided. The protuberance 154 covers a portion of the
extended portion 156 of the outlet portion 102 of the biological
fluid filter 100.
[0092] As seen in FIG. 16, a further plurality of ribs 142 is
provided on the interior surface of the bottom wall 150 to help
support the biological filter element 119 and provide flow in the
second or outlet chamber 115 of the biological fluid filter 100. An
upstanding ridge 157 is provided in a spaced apart relationship to
the upstanding sidewall 151. As with the circular ridges 147 and
155 when the outlet portion 22 and the inlet portion 21 are in
mating relationship, the down standing ridge 133 and the upstanding
ridge 157 will be in a 180 degree opposed relationship. As can be
seen in FIG. 15 these ridges will provide the pinch seals 160 for
the vent filter element 117 and the biological filter element 119.
An ultrasonic weld ridge 158 is provided to separate vent filter
117 and biological filter element 119, and to provide additional
support for the biological fluid filter 100.
[0093] Referring to FIGS. 22 and 23, there is shown a modification
of the biological fluid filter 100 previously described. In this
modification of the invention, the biological fluid filter 100 has
a housing 163, which may be constructed in a manner similar to that
just described, or may be constructed by other means well known in
the art. The housing has an inlet 164 to which a biological fluid
container of the type well known in the art would be in fluid
communication during operation. The housing 163 also has an outlet
165 through which the filtered fluid passes. The outlet 165 would
be in fluid communication with a biological receiving container
(not shown).
[0094] A filter element 166 would be sealingly mounted within the
housing between inlet 164 and outlet 165. In this modification of
the biological fluid filter 100, instead of there being a separate
and distinct vent filter element 117, the vent filter element 167
is embedded in the biological fluid filter element 166 i.e., the
filter medium is divided into two or more sections. The biological
filter element 166 may be made of a liquiphilic filter medium, and
the embedded vent filter element 167 may also be made of a
liquiphilic filter medium, surrounded by a solid or liquiphobic
barrier 168. In operation, this modification of the biological
fluid filter would operate in a similar manner to that just
described because of the liquiphilic nature of the biological
filter element 166, until the element was completely saturated. As
the blood was rising in the inlet chamber 161, any entrapped gas
would pass through the embedded vent filter element 167 until the
level of the blood surpassed the solid or liquiphobic barrier 168.
At this time, virtually all of the entrapped gas would be
downstream of the biological filter element 166, the element would
be completely saturated, and blood would now freely flow into the
outlet chamber 162.
[0095] Another modification of the biological fluid filter 100 is
shown in FIGS. 24 and 25. As before, there is a filter housing 163
having an inlet 164 communicating with an inlet chamber 161, and an
outlet 165 communicating with an outlet chamber 162. In this
modification of the invention, the biological filter element 166
has a first embedded liquiphilic gas vent 167 surrounded by a solid
barrier 168, and a second embedded liquiphobic gas vent 173 i.e.
the filter medium is divided into two or more sections, separated
form each other, in this case, three sections.
[0096] In operation, a biological fluid container known in the art
(not shown) will be in fluid communication with inlet 164. As blood
is released from the biological fluid container it will flow into
the inlet chamber 161 and come into contact with the bottom of the
biological fluid filter element 166. Since filter element 166 may
be a liquiphilic porous medium, the blood level may wick up in the
liquiphilic porous medium 166 faster than the level in the chamber
161. The blood will not pass through the liquiphobic second
embedded gas vent 173. The second embedded gas vent 173 will have
no effect on the operation of the biological fluid filter 100 while
the liquid level continues to rise in inlet chamber 161. However,
the difference between the embodiment of the invention shown in
FIGS. 22 and 23, and 24 and 25, becomes apparent when all of the
blood has been released from the biological filter container and
the level starts dropping in the inlet chamber 161. The vent filter
element 167 will stay wetted out as the level in the inlet chamber
161 drops because of the blood present in the outlet chamber 162.
However, as the level in the inlet chamber 161 continues to drop it
will drop below the level of the liquiphobic second embedded gas
vent 173. Since gas vent 173 did not wet out, when the blood level
drops, air will pass from the inlet chamber 161 through the second
embedded gas vent 173, and aid in draining the filter element 166,
as well as the outlet chamber 162, through the outlet 165.
[0097] Therefore, by carefully studying the problems present in
prior art biological filtration fluid systems; I have developed a
novel method and apparatus for biological fluid filtration.
[0098] In accordance with the provisions of the patent statutes,
the present invention has been described in what is considered to
represent its preferred embodiment. However, it should be noted
that the invention can be practiced otherwise than as specifically
illustrated and described without departing from its spirit or
scope.
* * * * *